<?xmlversion="1.0" encoding="US-ASCII"?>version='1.0' encoding='UTF-8'?> <!DOCTYPE rfcSYSTEM "rfc2629.dtd"> <?rfc toc="yes"?> <?rfc tocompact="yes"?> <?rfc tocdepth="3"?> <?rfc tocindent="yes"?> <?rfc symrefs="yes"?> <?rfc sortrefs="yes"?> <?rfc comments="yes"?> <?rfc inline="yes"?> <?rfc compact="yes"?> <?rfc subcompact="no"?>[ <!ENTITY nbsp " "> <!ENTITY zwsp "​"> <!ENTITY nbhy "‑"> <!ENTITY wj "⁠"> ]> <rfc xmlns:xi="http://www.w3.org/2001/XInclude" category="exp" docName="draft-ietf-6man-comp-rtg-hdr-10"ipr="trust200902">number="9631" consensus="true" ipr="trust200902" obsoletes="" updates="" submissionType="IETF" xml:lang="en" tocInclude="true" tocDepth="3" symRefs="true" sortRefs="true" version="3"> <front> <title abbrev="IPv6 Compact Routing Header">The IPv6 Compact Routing Header (CRH)</title> <seriesInfo name="RFC" value="9631"/> <author fullname="Ron Bonica" initials="R." surname="Bonica"> <organization>Juniper Networks</organization> <address> <postal> <street>2251 Corporate Park Drive</street> <city>Herndon</city> <code>20171</code><region>Virginia</region> <country>USA</country><region>VA</region> <country>United States of America</country> </postal> <email>rbonica@juniper.net</email> </address> </author> <author fullname="Yuji Kamite" initials="Y. " surname="Kamite"> <organization>NTT Communications Corporation</organization> <address> <postal> <street>3-4-1 Shibaura, Minato-ku</street><city>Tokyo</city><region>Tokyo</region> <code>108-8118</code> <country>Japan</country> </postal> <email>y.kamite@ntt.com</email> </address> </author> <author fullname="Andrew Alston" initials="A." surname="Alston"> <organization>Liquid Telecom</organization> <address> <postal><street/><city>Nairobi</city> <country>Kenya</country> </postal> <email>Andrew.Alston@liquidtelecom.com</email> </address> </author> <author fullname="Daniam Henriques" initials="D." surname="Henriques"> <organization>Liquid Telecom</organization> <address> <postal><street/><city>Johannesburg</city> <country>South Africa</country> </postal> <email>daniam.henriques@liquidtelecom.com</email> </address> </author> <author fullname="Luay Jalil" initials="L." surname="Jalil"> <organization>Verizon</organization> <address> <postal><street/><city>Richardson</city><region>Texas</region> <country>USA</country><region>TX</region> <country>United States of America</country> </postal> <email>luay.jalil@one.verizon.com</email> </address> </author> <dateday="30" month="May"month="August" year="2024"/><area>INT Area</area><area>INT</area> <workgroup>6man</workgroup> <keyword>IPv6</keyword> <keyword>Routing header</keyword> <abstract> <t>This document describes an experiment in which two new IPv6 Routing headers are implemented and deployed. Collectively, they are called the Compact RoutingHeadersHeader (CRH). Individually, they are called CRH-16 and CRH-32.</t> <t>One purpose of this experiment is to demonstrate that the CRH can be implemented and deployed in a production network. Another purpose is to demonstrate that the securityconsiderations,considerations described in thisdocument,document can be addressed withaccess control lists.Access Control Lists (ACLs). Finally, this document encourages replication of the experiment.</t> </abstract> </front> <middle> <section anchor="Intro"title="Introduction"> <t><xref target="RFC8200">IPv6 </xref>numbered="true" toc="default"> <name>Introduction</name> <t>IPv6 <xref target="RFC8200" format="default"></xref> source nodes use Routing headers to specify the path that a packet takes to its destination(s). The IETF has defined several Routing Types; see <xreftarget="IANA-RH">Routing types</xref>.target="IANA-RT" format="default"></xref>. This document defines two new Routingtypes.Types. Collectively, they are called the Compact RoutingHeadersHeader (CRH). Individually, they are called CRH-16 and CRH-32.</t> <t>The CRH allows IPv6 source nodes to specify the path that a packet takes to its destination. The CRH can be encoded in relatively few bytes. The following are reasons for encoding the CRH in as few bytes as possible:</t><t><list style="symbols"> <t>Many ASIC-based<ul spacing="normal"> <li> <t> Many forwarders based on Application-Specific Integrated Circuits (ASICs) copy headers from buffer memory to on-chip memory. As header sizes increase, so does the cost of this copy.</t> </li> <li> <t>Because<xref target="RFC8201">PathPath MTU Discovery(PMTUD)</xref>(PMTUD) <xref target="RFC8201" format="default"></xref> is not entirely reliable, many IPv6 hosts refrain from sending packets larger than the IPv6 minimum link MTU (i.e., 1280 bytes). When packets are small, the overhead imposed by large RoutingHeadersheaders is excessive.</t></list>This</li> </ul> <t>This document describes an experimentwhose purposes are:</t> <t><list style="symbols">with the following purposes:</t> <ul spacing="normal"> <li> <t>To demonstrate that the CRH can be implemented anddeployed.</t>deployed</t> </li> <li> <t>To demonstrate that the securityconsiderations,considerations described in thisdocument,document can be addressed withaccess control lists.</t>ACLs</t> </li> <li> <t>To encourage replication of theexperiment.</t> </list></t>experiment</t> </li> </ul> </section> <section anchor="ReqLang"title="Requirements Language"> <t>Thenumbered="true" toc="default"> <name>Requirements Language</name> <t> The key words"MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY","<bcp14>MUST</bcp14>", "<bcp14>MUST NOT</bcp14>", "<bcp14>REQUIRED</bcp14>", "<bcp14>SHALL</bcp14>", "<bcp14>SHALL NOT</bcp14>", "<bcp14>SHOULD</bcp14>", "<bcp14>SHOULD NOT</bcp14>", "<bcp14>RECOMMENDED</bcp14>", "<bcp14>NOT RECOMMENDED</bcp14>", "<bcp14>MAY</bcp14>", and"OPTIONAL""<bcp14>OPTIONAL</bcp14>" in this document are to be interpreted as described in BCP 14 <xreftarget="RFC2119">BCP 14</xref>target="RFC2119"/> <xref target="RFC8174"/> when, and only when, they appear in all capitals, as shownhere.</t>here. </t> </section> <sectiontitle="Thenumbered="true" toc="default"> <name>The Compact RoutingHeaders (CRH)">Header (CRH)</name> <t>Both CRH versions (i.e., CRH-16 and CRH-32) contain the following fields:</t><t><list style="symbols"> <t>Next Header - Defined<ul spacing="normal"> <li>Next Header, as defined in <xreftarget="RFC8200"/>.</t> <t>Hdrtarget="RFC8200" format="default"/></li> <li>Hdr ExtLen - DefinedLen, as defined in <xreftarget="RFC8200"/>.</t> <t>Routing Type - Definedtarget="RFC8200" format="default"/></li> <li>Routing Type, as defined in <xreftarget="RFC8200"/>.target="RFC8200" format="default"/> (CRH-16 value is5.5, and CRH-32 value is6).</t> <t>Segments Left - Defined6.)</li> <li>Segments Left, as defined in <xreftarget="RFC8200"/>.</t> <t>Type-specific Data - Describedtarget="RFC8200" format="default"/></li> <li>type-specific data, as described in <xreftarget="RFC8200"/>.</t> </list></t>target="RFC8200" format="default"/></li> </ul> <t>In the CRH, theType-specifictype-specific data field contains a list of CRH Segment Identifiers (CRH SIDs). Each CRH SID identifies an entry in the<xref target="crh-fib">CRHCRH Forwarding Information Base (CRH-FIB)</xref>.(<xref target="crh-fib" format="default"></xref>). Each CRH-FIB entry identifies an interface on the path that the packet takes to its destination.</t> <t>CRH SIDs are listed in reverse order. So, the first CRH SID in the list represents the final interface in the path. Because CRH SIDs are listed in reverse order, the Segments Left field can be used as an index into the CRH SID list. In this document, the "current CRH SID" is the CRH SID list entry referenced by the Segments Left field.</t> <t>The first CRH SID in the path is omitted from the list unless there is some reason to preserve it. See <xreftarget="Examples">target="Examples" format="default"> </xref> for an example.</t> <t>In the<xref target="CRHFig16">CRH-16</xref>,CRH-16 (<xref target="CRHFig16" format="default"></xref>), each CRH SID is encoded in16-bits.16 bits. In the<xref target="CRHFig32">CRH-32</xref>,CRH-32 (<xref target="CRHFig32" format="default"></xref>), each CRH SID is encoded in32-bits.</t>32 bits.</t> <t>In all cases, the CRHMUST<bcp14>MUST</bcp14> end on a 64-bit boundary. So, theType- specifictype-specific data fieldMUST<bcp14>MUST</bcp14> be padded with zeros if the CRH would otherwise not end on a 64-bit boundary.</t> <figure anchor="CRHFig16"> <name>CRH-16</name> <artwork name="" type="" align="left"anchor="CRHFig16" title="CRH-16"> <artwork><![CDATA[alt=""><![CDATA[ 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Next Header | Hdr Ext Len | Routing Type | Segments Left | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | SID[0] | SID[1] | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-| | ......... +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- ]]></artwork> </figure> <figure anchor="CRHFig32"> <name>CRH-32</name> <artwork name="" type="" align="left"anchor="CRHFig32" title="CRH-32"> <artwork><![CDATA[alt=""><![CDATA[ 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Next Header | Hdr Ext Len | Routing Type | Segments Left | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + SID[0] + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + SID[1] + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ......... +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- ]]></artwork> </figure> </section> <section anchor="crh-fib"title="Thenumbered="true" toc="default"> <name>The CRH Forwarding Information Base(CRH-FIB)">(CRH-FIB)</name> <t>Each CRH SID identifies a CRH-FIB entry.</t> <t>Each CRH-FIB entry contains:</t><t><list style="symbols"><ul spacing="normal"> <li> <t>An IPv6address.</t>address</t> </li> <li> <t>A topologicalfunction.</t>function</t> </li> <li> <t>Arguments for the topologicalfunction. (Optional).</t> </list></t>function (optional)</t> </li> </ul> <t>The IPv6 address can be a Global Unicast Address (GUA), aLink LocalLink-Local Unicastaddress (LLU),(LLU) address, or a Unique Local Address (ULA). When the IPv6 address is the final address in a path, it can also be a multicast address.</t> <t>The topological function specifies how the processing node forwards the packet to the interface identified by the IPv6 address. The following are examples:</t><t><list style="symbols"><ul spacing="normal"> <li> <t>Forward the packet through the least-cost path to the interface identified by the IPv6 address (i.e., loose source routing).</t> </li> <li> <t>Forward the packet through a specified interface to the interface identified by the IPv6 address(i.e.,strict(i.e., strict sourcerouting)</t> </list></t>routing).</t> </li> </ul> <t>Some topological functions require parameters. For example, a topological function might require a parameter that identifies the interface through which the packet is forwarded.</t> <t>The CRH-FIB can bepopulated:</t> <t><list style="symbols"> <t>By anpopulated by:</t> <ul spacing="normal"> <li> <t>An operator, using a Command Line Interface(CLI).</t> <t>By a(CLI)</t> </li> <li> <t>A controller, using the<xref target="RFC5440">PathPath Computation Element(PCE)Communication Protocol (PCEP)</xref><xref target="RFC5440" format="default"></xref> or the<xref target="RFC6241">NetworkNetwork Configuration Protocol(NETCONF)</xref>.</t> <t>By a(NETCONF) <xref target="RFC6241" format="default"></xref></t> </li> <li> <t>A distributed routingprotocolprotocol, such as those defined in <xreftarget="ISO10589-Second-Edition"/>,target="ISO10589-Second-Edition" format="default"/>, <xreftarget="RFC5340"/>,target="RFC5340" format="default"/>, and <xreftarget="RFC4271"/>.</t> </list></t>target="RFC4271" format="default"/></t> </li> </ul> <t>The above-mentioned mechanisms are not defined here and are beyond the scope of thisdocument</t>document.</t> </section> <sectiontitle="Processing Rules">numbered="true" toc="default"> <name>Processing Rules</name> <t>The following rules describe CRHprocessing:<list style="symbols">processing:</t> <ul spacing="normal"> <li> <t>If Hdr Ext Len indicates that the CRH is larger than the implementation can process, discard the packet and send an ICMPv6 <xreftarget="RFC4443">ICMPv6 </xref>target="RFC4443" format="default"></xref> Parameter Problem, Code 0, message to the Source Address, pointing to the Hdr Ext Len field.</t> </li> <li> <t>Compute L, the minimum CRH length( <xref target="SLLeng">(<xref target="SLLeng" format="default"> </xref>).</t> </li> <li> <t>If L is greater than Hdr Ext Len, discard the packet and send an ICMPv6 Parameter Problem, Code 6, message to the Source Address, pointing to the Segments Left field.</t> </li> <li> <t>Decrement Segments Left.</t> </li> <li> <t>Search for the current CRH SID in the CRH-FIB. In this document, the "current CRH SID" is the CRH SID list entry referenced by the Segments Left field.</t> </li> <li> <t>If the search does not return a CRH-FIB entry, discard the packet and send an ICMPv6 Parameter Problem, Code 0, message to the Source Address, pointing to the current SID.</t> </li> <li> <t>If Segments Left is greater than 0 and the CRH-FIB entry contains a multicast address, discard the packet and send an ICMPv6 Parameter Problem, Code 0, message to the Source Address, pointing to the current SID. (This prevents packet storms.)</t> </li> <li> <t>Copy the IPv6 address from the CRH-FIB entry to the Destination Address field in the IPv6 header.</t> </li> <li> <t>Submit the packet, its topologicalfunctionfunction, and its parameters to the IPv6module. See NOTE.</t> </list>NOTE:module.</t> </li> </ul> <aside><t>NOTE: By default, the IPv6 module determines thenext-hopnext hop and forwards the packet. However, the topological function may elicit another behavior. For example, the IPv6 module may forward the packet through a specified interface.</t> </aside> <section anchor="SLLeng"title="Computingnumbered="true" toc="default"> <name>Computing Minimum CRHLength">Length</name> <t>The algorithm described in this section accepts the following CRH fields as its input parameters:</t><t><list style="symbols"><ul spacing="normal"> <li> <t>Routing Type (i.e., CRH-16 orCRH-32).</t>CRH-32)</t> </li> <li> <t>SegmentsLeft.</t> </list></t>Left</t> </li> </ul> <t>It yields L, the minimum CRH length. The minimum CRH length is measured in 8-octet units, not including the first 8 octets.</t><figure> <artwork align="center"><![CDATA[<CODE BEGINS><sourcecode name="" type="pseudocode" markers="true"><![CDATA[ switch(Routing Type) { case CRH-16: if (Segments Left <= 2) return(0) sidsBeyondFirstWord = Segments Left - 2; sidPerWord = 4; case CRH-32: if (Segments Left <= 1) return(0) sidsBeyondFirstWord = Segments Left - 1; sidsPerWord = 2; case default: return(0xFF); } words = sidsBeyondFirstWord div sidsPerWord; if (sidsBeyondFirstWord mod sidsPerWord) words++; return(words)<CODE ENDS> ]]></artwork> </figure>]]></sourcecode> </section> </section> <sectiontitle="Mutability">numbered="true" toc="default"> <name>Mutability</name> <t>In the CRH, the Segments Left field is mutable. All remaining fields are immutable.</t> </section> <sectiontitle="Applications And SIDs">numbered="true" toc="default"> <name>Applications and CRH SIDs</name> <t>A CRH contains one or more CRH SIDs. Each CRH SID is processed by exactly one CRH-configured router whose one address matches the packetdestination address.</t>Destination Address.</t> <t>Therefore, a CRH SID is not required to have domain-wide significance. Applicationscan:<list style="symbols"> <t>Allocatecan allocate CRH SIDs so that they have either domain-widesignificance.</t> <t>Allocate CRH SIDs so that they haveor node-local significance.</t></list></t></section> <sectiontitle="Operational Considerations"> <t><xref target="RFC2151">PINGnumbered="true" toc="default"> <name>Operational Considerations</name> <t>PING andTRACEROUTE </xref>Traceroute <xref target="RFC2151" format="default"></xref> both operate correctly in the presence of the CRH. TCPDUMP and Wireshark have been extended to support the CRH.</t> <t>PING andTRACEROUTETraceroute report 16-bit CRH SIDs forCRH-16,CRH-16 and 32-bit CRH SIDs for CRH-32. It is recommended that the experimental versions of PING use thetexttextual representations described in <xreftarget="TR">target="TR" format="default"> </xref>.</t> </section> <section anchor="TR"title="Textual Representation">numbered="true" toc="default"> <name>Textual Representations</name> <t>A 16-bit CRH SID can be represented by fourlower-caselowercase hexadecimal digits. Leading zerosSHOULD<bcp14>SHOULD</bcp14> be omitted. However, the all-zeros CRH SIDMUST<bcp14>MUST</bcp14> be represented by a single 0. The following are examples:</t><t><list style="symbols"><ul spacing="normal"> <li> <t>beef</t> </li> <li> <t>eef</t> </li> <li> <t>0</t></list></t></li> </ul> <t>A 16-bit CRH SID also can be represented in dotted-decimal notation. The following areexamples:<list style="symbols">examples:</t> <ul spacing="normal"> <li> <t>192.0</t> </li> <li> <t>192.51</t></list></t></li> </ul> <t>A 32-bit CRH SID can be represented by fourlower-caselowercase hexadecimal digits, a colon (:), and another fourlower-caselowercase hexadecimal digits. Leading zerosMUST<bcp14>MUST</bcp14> be omitted. The following are examples:</t><t><list style="symbols"><ul spacing="normal"> <li> <t>dead:beef</t> </li> <li> <t>ead:eef</t> </li> <li> <t>:beef</t> </li> <li> <t>beef:</t> </li> <li> <t>:</t></list>A</li> </ul> <t>A 32-bit CRH SID can also berepresentrepresented in dotted-decimal notation. The following areexamples:<list style="symbols">examples:</t> <ul spacing="normal"> <li> <t>192.0.2.1</t> </li> <li> <t>192.0.2.2</t> </li> <li> <t>192.0.2.3</t></list></t></li> </ul> </section> <section anchor="Security"title="Security Considerations">numbered="true" toc="default"> <name>Security Considerations</name> <t>In this document, one node trusts another only if both nodes are operated by the same party. A node determines whether it trusts another node by examining its IP address. In many networks, operators number their nodesfromusing a small number of prefixes. This facilitates identification of trusted nodes.</t> <t>A node can encounter security vulnerabilities when it processes a RoutingHeaderheader that originated on an untrusted node <xreftarget="RFC5095"/>.target="RFC5095" format="default"/>. Therefore, nodesMUST<bcp14>MUST</bcp14> deploy ACLs that discard packets containing the CRH when both of the following conditions are true:</t><list style="symbols"><ul spacing="normal"> <li> <t>The Source Address does not identify an interface on a trusted node.</t> </li> <li> <t>The Destination Address identifies an interface on the local node.</t></list></li> </ul> <t>The above-mentioned ACLs do not protect the node from attack packets that contain a forged (i.e., spoofed) Source Address. In order to mitigate this risk, nodesMAY<bcp14>MAY</bcp14> also discard packets containing the CRH when all of the following conditions are true:</t><list style="symbols"><ul spacing="normal"> <li> <t>The Source Address identifies an interface on a trusted node.</t> </li> <li> <t>The Destination Address identifies an interface on the local node.</t> </li> <li> <t>The packet does not pass an<xref target="RFC8704">EnhancedEnhanced Feasible-Path Unicast Reverse Path Forwarding(RPF) </xref>,</t> </list>(EFP-uRPF) <xref target="RFC8704" format="default"></xref> check.</t> </li> </ul> <t>TheRPFEFP-uRPF check eliminates some, but notallall, packets with forgedsource addresses.Source Addresses. Therefore, a network operator that deploys CRHMUST<bcp14>MUST</bcp14> implementAccess Control Lists (ACL)ACLs on each of its edge nodes. The ACL discards packets whosesource addressSource Address identifies an interface on a trusted node.</t> <t>The CRH is compatible with end-to-end IPv6 Authentication Header (AH) <xreftarget="RFC4302"></xref>target="RFC4302" format="default"/> processing. This isbecasuebecause the source node calculates the Integrity Check Value (ICV) over the packet as it arrives at the destination node.</t> </section> <sectiontitle="Implementation and Deployment Status"> <t>Juniper Networks has produced experimental implementations of the CRH on the MX-series (ASIC-based) router</t> <t>Liquid Telecom has produced experimental implementations of the CRH on software based routers.</t> <t>The CRH has carried non-production traffic in CERNET and Liquid Telecom.</t> <t>Interoperability among these implementations has not yet been demonstrated.</t> </section> <section title="Experimental Results">numbered="true" toc="default"> <name>Experimental Results</name> <t>Parties participating in this experiment should publish experimental results within one year of the publication of this document. Experimental results should address the following:</t><t><list style="symbols"><ul spacing="normal"> <li> <t>Effort required todeploy<list style="symbols">deploy</t> <ul spacing="normal"> <li> <t>Was deployment incremental or network-wide?</t> </li> <li> <t>Was there a need to synchronize configurations at eachnodenode, or could nodes be configuredindependently</t>independently?</t> </li> <li> <t>Did the deployment require a hardware upgrade?</t> </li> <li> <t>Did the CRH SIDs have domain-wide or node-local significance?</t></list></t></li> </ul> </li> <li> <t>Effort required to secure</t> </li> <li> <t>Performance impact</t> </li> <li> <t>Effectiveness of risk mitigation with ACLs</t> </li> <li> <t>Cost of risk mitigation with ACLs</t> </li> <li> <t>Mechanism used to populate theFIB</t>CRH-FIB</t> </li> <li> <t>Scale of deployment</t><t>Interoperability<list style="symbols"></li> <li> <t>Interoperability</t> <ul spacing="normal"> <li> <t>Did you deploy twointer-operableinteroperable implementations?</t> </li> <li> <t>Did you experience interoperability problems?</t> </li> <li> <t>Did implementations generally implement the same topological functions with identical arguments?</t> </li> <li> <t>Were topological function semantics identical on each implementation?</t></list></t></li> </ul> </li> <li> <t>Effectiveness and sufficiency ofOAM mechanism<list style="symbols">Operations, Administration, and Maintenance (OAM) mechanisms</t> <ul spacing="normal"> <li> <t>Did PING work?</t> </li> <li> <t>DidTRACEROUTETraceroute work?</t> </li> <li> <t>Did Wireshark work?</t> </li> <li> <t>Did TCPDUMP work?</t></list></t> </list></t></li> </ul> </li> </ul> </section> <sectiontitle="IANA Considerations"> <t>This document makesnumbered="true" toc="default"> <name>IANA Considerations</name> <t>IANA has registered the followingregistrationsin the "Routing Types" subregistry within the "Internet Protocol Version 6 (IPv6) Parameters""Routing Types" subregistry maintained by IANA:</t> <figure> <artwork><![CDATA[ +-------+------------------------------+---------------+ | Value | Description | Reference | +=======+==============================+===============+ | 5 | CRH-16 | This document | +-------+------------------------------+---------------+ | 6 | CRH-32 | This document | +-------+------------------------------+---------------+ ]]></artwork> </figure> <t/> </section> <section anchor="Acknowledgements" title="Acknowledgements"> <t>Thanks to Dr. Vanessa Ameen, Dale Carder, Brian Carpenter, Adrian Farrel, Fernando Gont, Naveen Kottapalli, Joel Halpern, Mark Smith, Reji Thomas, Tony Li, Xing Li, Gerald Schmidt, Nancy Shaw, Ketan Talaulikar, and Chandra Venkatraman for their contributions to this document.</t> </section> <section title="Contributors"> <t><list style="empty"> <t>Gang Chen</t> <t>Baidu</t> <t>No.10 Xibeiwang East Road Haidian District</t> <t>Beijing 100193 P.R. China</t> <t>Email: phdgang@gmail.com</t> </list><list style="empty"> <t/> </list><list style="empty"> <t>Yifeng Zhou</t> <t>ByteDance</t> <t>Building 1, AVIC Plaza, 43 N 3rd Ring W Rd Haidian District</t> <t>Beijing 100000 P.R. China</t> <t>Email: yifeng.zhou@bytedance.com</t> </list><list style="empty"> <t/> </list><list style="empty"> <t>Gyan Mishra</t> <t>Verizon</t> <t>Silver Spring, Maryland, USA</t> <t>Email: hayabusagsm@gmail.com</t> </list></t>registry:</t> <table anchor="iana-table"> <name></name> <thead> <tr> <th>Value</th> <th>Description</th> <th>Reference</th> </tr> </thead> <tbody> <tr> <td>5</td> <td>CRH-16</td> <td>RFC 9631</td> </tr> <tr> <td>6</td> <td>CRH-32 </td> <td>RFC 9631</td> </tr> </tbody> </table> </section> </middle> <back><references title="Normative References"> <?rfc include="reference.RFC.2119"?> <?rfc include='reference.RFC.8174'?> <?rfc include='reference.RFC.8200'?> <?rfc include='reference.RFC.4443'?> <?rfc include='reference.RFC.5095'?> <?rfc include='reference.RFC.4302'?> <?rfc ?><references> <name>References</name> <references> <name>Normative References</name> <xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.2119.xml"/> <xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.8174.xml"/> <xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.8200.xml"/> <xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.4443.xml"/> <xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.5095.xml"/> <xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.4302.xml"/> </references><references title="Informative References"> <?rfc include='reference.RFC.2151'?> <?rfc include='reference.RFC.5440'?> <?rfc include='reference.RFC.6241'?> <?rfc include='reference.RFC.5340'?> <?rfc include='reference.RFC.4271'?> <?rfc include='reference.RFC.8201'?> <?rfc include='reference.RFC.8704'?> <?rfc ?><references> <name>Informative References</name> <xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.2151.xml"/> <xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.5440.xml"/> <xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.6241.xml"/> <xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.5340.xml"/> <xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.4271.xml"/> <xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.8201.xml"/> <xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.8704.xml"/> <referenceanchor="IANA-RH" target="https://www.iana.org/assignments/ipv6-parameters/ipv6-parameters.xhtml#ipv6-parameters-3">anchor="IANA-RT" target="https://www.iana.org/assignments/ipv6-parameters"> <front> <title>RoutingHeaders</title> <author fullname="" initials="" surname="">Types</title> <author> <organization>IANA</organization> </author><date month="" year=""/></front> </reference> <reference anchor="ISO10589-Second-Edition"target="">target="https://www.iso.org/standard/30932.html"> <front><title>"Intermediate system<title>Information technology - Telecommunications and information exchange between systems - Intermediate System to IntermediatesystemSystem intra-domain routeing information exchange protocol for use in conjunction with the protocol for providing the connectionless-modeNetwork Servicenetwork service (ISO8473)", ISO/IEC 10589:2002, Second Edition,</title> <author fullname="" initials="" surname=""> <organization>International Organization for Standardization</organization>8473)</title> <author> <organization>ISO/IEC</organization> </author> <date month="November"year="2001"/>year="2002"/> </front> <refcontent>Second Edition</refcontent> <seriesInfo name="ISO/IEC" value="10589:2002"/> </reference> </references> </references> <section anchor="Examples"title="CRHnumbered="true" toc="default"> <name>CRH ProcessingExamples">Examples</name> <t>This appendix demonstrates CRH processing in the following scenarios:</t><t><list style="symbols"> <t><xref target="LSRP">The<ul spacing="normal"> <li> <t>The CRH SID list contains one entry for each segment in the path</xref>.</t> <t><xref target="LSR">The(<xref target="LSRP" format="default"></xref>).</t> </li> <li> <t>The CRH SID list omits the first entry in the path</xref>.</t> </list></t>(<xref target="LSR" format="default"></xref>).</t> </li> </ul> <t><xref target="RefTopo" format="default"/> provides a reference topology that is used in all examples, and <xref target="lsid" format="default"/> describes two entries that appear in each node's CRH-FIB.</t> <figurealign="center" anchor="RefTopo" title="Reference Topology"> <artwork><![CDATA[anchor="RefTopo"> <name>Reference Topology</name> <artwork name="" type="" align="left" alt=""><![CDATA[ ----------- ----------- ----------- |Node: S | |Node: I1 | |Node: I2 | |Loopback: |---------------|Loopback: |---------------|Loopback: | |2001:db8::a| |2001:db8::1| |2001:db8::2| ----------- ----------- ----------- | | | ----------- | | |Node: D | | ---------------------|Loopback: |--------------------- |2001:db8::b| ----------- ]]></artwork> </figure><t/> <t><xref target="RefTopo"/> provides a reference topology that is used in all examples.</t> <texttable<table anchor="lsid"title="Node SIDs"> <ttcol>SID</ttcol> <ttcol>IPv6 Address</ttcol> <ttcol>Forwarding Method</ttcol> <c>2</c> <c>2001:db8::2</c> <c>Least-cost path</c> <c>11</c> <c>2001:db8::b</c> <c>Least-cost path</c> </texttable> <t><xref target="lsid"/> describes two entries that appear in each node's CRH-FIB.</t> <t/>align="center"> <name>Node SIDs</name> <thead> <tr> <th align="left">SID</th> <th align="left">IPv6 Address</th> <th align="left">Forwarding Method</th> </tr> </thead> <tbody> <tr> <td align="left">2</td> <td align="left">2001:db8::2</td> <td align="left">Least-cost path</td> </tr> <tr> <td align="left">11</td> <td align="left">2001:db8::b</td> <td align="left">Least-cost path</td> </tr> </tbody> </table> <section anchor="LSRP"title="Thenumbered="true" toc="default"> <name>The CRH SIDList Contains One Entry For Each Segment In The Path">list contains one entry for each segment in the path.</name> <t>In this example, Node S sends a packet to NodeD,D viaI2. In this example,I2, and I2 appears in the CRH segment list.</t><texttable> <ttcol>As the packet travels<table align="center"> <name>Packet Travels from S toI2:</ttcol> <ttcol/> <c>SourceI2</name> <tbody> <tr> <td align="left">Source Address =2001:db8::a</c> <c>Segments2001:db8::a</td> <td align="left">Segments Left =1</c> <c>Destination1</td> </tr> <tr> <td align="left">Destination Address =2001:db8::2</c> <c>SID[0] = 11</c> <c/> <c>SID[1] = 2</c> </texttable> <texttable> <ttcol>As the packet travels2001:db8::2</td> <td align="left">SID[0] = 11</td> </tr> <tr> <td align="left"/> <td align="left">SID[1] = 2</td> </tr> </tbody> </table> <table align="center"> <name>Packet Travels from I2 toD:</ttcol> <ttcol/> <c>SourceD</name> <tbody> <tr> <td align="left">Source Address =2001:db8::a</c> <c>Segments2001:db8::a</td> <td align="left">Segments Left =0</c> <c>Destination0</td> </tr> <tr> <td align="left">Destination Address =2001:db8::b</c> <c>SID[0] = 11</c> <c/> <c>SID[1] = 2</c> </texttable>2001:db8::b</td> <td align="left">SID[0] = 11</td> </tr> <tr> <td align="left"/> <td align="left">SID[1] = 2</td> </tr> </tbody> </table> </section> <section anchor="LSR"title="Thenumbered="true" toc="default"> <name>The CRH SIDList Omits The First Entry In The Path ">list omits the first entry in the path.</name> <t>In this example, Node S sends a packet to NodeD,D viaI2. In this example,I2, and I2 does not appear in the CRH segment list.</t><texttable> <ttcol>As the packet travels<table align="center"> <name>Packet Travels from S toI2:</ttcol> <ttcol/> <c>SourceI2</name> <tbody> <tr> <td align="left">Source Address =2001:db8::a</c> <c>Segments2001:db8::a</td> <td align="left">Segments Left =1</c> <c>Destination1</td> </tr> <tr> <td align="left">Destination Address =2001:db8::2</c> <c>SID[0] = 11</c> </texttable> <t/> <texttable> <ttcol>As the packet travels2001:db8::2</td> <td align="left">SID[0] = 11</td> </tr> </tbody> </table> <table align="center"> <name>Packet Travels from I2 toD:</ttcol> <ttcol/> <c>SourceD</name> <tbody> <tr> <td align="left">Source Address =2001:db8::a</c> <c>Segments2001:db8::a</td> <td align="left">Segments Left =0</c> <c>Destination0</td> </tr> <tr> <td align="left">Destination Address =2001:db8::b</c> <c>SID[0] = 11</c> </texttable> <t/>2001:db8::b</td> <td align="left">SID[0] = 11</td> </tr> </tbody> </table> </section> </section> <section anchor="Acknowledgements" numbered="false" toc="default"> <name>Acknowledgements</name> <t>Thanks to <contact fullname="Dr. Vanessa Ameen"/>, <contact fullname="Dale Carder"/>, <contact fullname="Brian Carpenter"/>, <contact fullname="Adrian Farrel"/>, <contact fullname="Fernando Gont"/>, <contact fullname="Joel Halpern"/>, <contact fullname="Naveen Kottapalli"/>, <contact fullname="Tony Li"/>, <contact fullname="Xing Li"/>, <contact fullname="Gerald Schmidt"/>, <contact fullname="Nancy Shaw"/>, <contact fullname="Mark Smith"/>, <contact fullname="Ketan Talaulikar"/>, <contact fullname="Reji Thomas"/>, and <contact fullname="Chandra Venkatraman"/> for their contributions to this document.</t> </section> <section numbered="false" toc="default"> <name>Contributors</name> <contact fullname="Gang Chen" > <organization>Baidu</organization> <address> <postal> <street>No.10 Xibeiwang East Road</street> <city>Beijing</city> <cityarea>Haidian District</cityarea> <region></region><code>100193</code> <country>China</country> </postal> <email>phdgang@gmail.com</email> </address> </contact> <contact fullname="Yifeng Zhou" > <organization>ByteDance</organization> <address> <postal> <street>43 N 3rd Ring W Rd</street> <extaddr>Building 1, AVIC Plaza</extaddr> <cityarea>Haidian District</cityarea> <city>Beijing</city> <region></region><code>100000</code> <country>China</country> </postal> <email>yifeng.zhou@bytedance.com</email> </address> </contact> <contact fullname="Gyan Mishra" > <organization>Verizon</organization> <address> <postal> <street></street> <city>Silver Spring</city> <region>MD</region><code></code> <country>United States of America</country> </postal> <email>hayabusagsm@gmail.com</email> </address> </contact> </section> </back> </rfc>